Effort of past orient travelling (8)
I believe the answer is:
exertion
'effort' is the definition.
(I know that effort can be written as exertion)
'past orient travelling' is the wordplay.
'past' becomes 'ex' (similar in meaning).
'travelling' is an anagram indicator.
'orient' with letters rearranged gives 'ertion'.
'ex'+'ertion'='EXERTION'
'of' is the link.
(Other definitions for exertion that I've seen before include "Strenuous activity" , "Great effort" , "Physical or mental effort" , "Strain" , "labour" .)